Rotary lobe pumps help solve difficult biosolids pumping application requirements

By Jeff Bye

Operations staff at one wastewater treatment plant were initially using a reciprocating pump to move raw sludge and biosolids from primary clarifiers to the anaerobic digesters. The percentage of solids was approximately 4% by volume and, in some cases, could get as high as 6% by volume.

Due to the lack of a screen, the size of the solids could not be controlled, which often caused the pump to jam. The wear on the moving parts was excessive and maintenance, requiring replacement of parts, was frequent and expensive. Spare parts were large and heavy because of the general design of the reciprocating pump. This created safety issues during handling, in addition to the cost.

The plant is a relatively small one, so space is a consideration. The reciprocating pumps not only required a large footprint for their installation, but also additional room for maintenance work. The plant is managed by three people, and the frequent maintenance also resulted in schedule disruption for them, as they handle multiple tasks.

Centrifugal pumps were installed as an alternative, but they presented their own set of problems. The centrifugal pumps had to be sized much larger as a result of their low efficiencies and ended up raising the cost of power. Varying solid content in the sludge also caused issues.

To solve these problems, a NETZSCH Tornado® T2 rotary lobe pump was installed with temporary piping, until a second pump was purchased and made operational later.

After both pumps were in place, the piping was converted to a permanent arrangement. The pumps were coupled with variable frequency drives and a flow meter was added to optimize flow control. The two pumps fitted nicely on just one of the old pump pads, as they have a small footprint, which provides extra space around the installation.

The first pump has been operating for more than two years with no problems. During this time, it has been periodically inspected, but did not require any maintenance nor replacement of parts.

At a nearby community, the wastewater treatment plant was experiencing similar difficulties. The plant used plunger type pumps that had been rebuilt many times throughout their years of usage.

They were installed in a small room which made service a struggle. The pumps were piped together with cross tie piping so that the primary and secondary sludge pumps could back each other up. This significantly reduced access to the pumps, making maintenance extremely difficult.

When the primary sludge pump was again in need of a rebuild, requiring a piston, packing gland, packing, and several other components, operations staff discovered that the price of a new NETZSCH Tornado T2 rotary lobe pump was close to the price of just the spare parts for the plunger pump.

The existing primary plunger pump had to be disassembled in parts for removal so that the new rotary lobe pumps could be installed. Piping was also modified to enable better access to both of the pumps. Now, each pump can easily be inspected and serviced.

The layout of the pump systems was modified to allow easy access and more space for inspection, maintenance and service. To date, the pumps have been operating without trouble and there has been no need for maintenance.

These rotary lobe pumps require only a small footprint, while providing easy access for maintenance.

Jeff Bye is with NETZSCH. For more information, contact Jason Balcerczyk, NETZSCH Canada. Email: jason.balcerczyk@netzsch.com

Brantford WWTP earns perfect score in Grand River program

By ES&E Staff

The Ontario City of Brantford earned a perfect score at a recent workshop because the effluent from its wastewater treatment system was consistently meeting a very high standard when discharged into the Grand River.

The Grand River Watershed-Wide Wastewater Optimization Program workshop reviews the performance of wastewater treatment facilities on an annual basis and awards points based on defined criteria that can earn gold, silver or bronze recognition.

The perfect score means that the Brantford facility, which serves nearly 100,000 residents and was commissioned in 1960, earned gold recognition.

The facility employs a stream-based

The Grand River flowing through Brantford,

Ontario. Credit: Balcer, CC BY-SA 3.0, via Wikimedia Commons

wastewater collection and treatment system that collects wastewater from the east and west sides of the Grand River, according to city documents. The collection system generally drains from the north to the south and from west of the Grand River to the east.

“The existing network also includes siphons which convey flow under the Grand River in four locations,” states Brantford’s 2014 Master Plan.

The treatment plant has nine wastewater pumping stations and gravity trunk sewers within the city’s wastewater collection system. The plant’s treatment works consist of two primary clarifiers equipped with raw sludge pumps, two aeration tanks and two secondary clarifiers.

Over the last several years, there has been a steady decline in electricity usage at the WWTP as a result of replacement of old blowers and aeration piping.

A goal of the workshop program is for all treatment facilities that discharge into the Grand River to achieve regulatory compliance and more stringent voluntary effluent targets for phosphorus and ammonia to help the Lake Erie ecosystem. Throughout the year, the program provides technical support to facilities in need and conducts workshops to improve operational knowledge.

HOW EFFICIENT IS YOUR AERATION PROCESS?

LET’S TALK

Scott McLeod, Aerzen Canada Sales Manager

+1 450 424 3966 ext.226 scott.mcleod@aerzen.com

Real e ciency means operating the consumption profiles in wastewater treatment plants with precision. Aeration consumes up to 80% of total energy requirements; the greatest savings potential can therefore be found here. With our Performance3 product portfolio consisting of Blower, Hybrid, and Turbo technologies, we always find the most e cient and tailor-made solution for you. Benefit from up to 30% energy savings! LET’S TALK! We’ll be happy to advise you!

www.aerzen.ca